ATxmega256A3 Atmel Corporation, ATxmega256A3 Datasheet - Page 24

• Manufacturer Part Number: ATxmega256A3
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 50
• Ext Interrupts: 50
• Usb Speed: No
• Usb Interface: No
• Spi: 10
• Twi (i2c): 2
• Uart: 7
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

4.10.1
4.11
4.12
4.13
8077H–AVR–12/09
Memory Timing
Device ID
JTAG Disable
Bus Priority
Figure 4-3.
When several masters request access to the same bus, the bus priority is in the following order
(from higher to lower priority)
Read and write access to the I/O Memory takes one CPU clock cycle. Write to SRAM takes one
cycle and read from SRAM takes two cycles. For burst read (DMA), new data is available every
cycle. EEPROM page load (write) takes one cycle and three cycles are required for read. For
burst read, new data is available every second cycle. External memory has multi-cycle read and
write. The number of cycles depends on type of memory and configuration of the External Bus
Interface. Refer to the instruction summary for more details on instructions and instruction
timing.
Each device has a three-byte device ID which identifies the device. These registers identify
Atmel as the manufacturer of the device and the device type. A separate register contains the
revision number of the device.
It is possible to disable the JTAG interface from the application software. This will prevent all
external JTAG access to the memory, until the next device reset or if JTAG is enabled again
1. Bus Master with ongoing access
2. Bus Master with ongoing burst
3. Bus Master requesting burst access
4. Bus Master requesting bus access
a. Alternating DMA Controller Read and DMA Controller Write when the they access
a. CPU has priority
a. CPU has priority
the same Data Memory section.
DMA Controller
DMA Controller
Bus Access
Read
Write
CPU
Data Memory Bus
I/O Memory
EEPROM
External
Memory
SRAM
XMEGA A
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